Email Problems with OS 10.10 Yosemite

[kn]

It's hard to resist updates from the App Store...

This update seems to have done something to screw up Mail. After everything I could think of, I spent an hour with a Telus tech and the eventual answer was to wait for an Apple update...

They finally got a workaround for the imap server but the smtp server is not recognized. Webmail and my iPhone are fine but not my MacBook Pro.

First world problems...

[kn]

I finally got email working only by enabling "Allow insecure authentication" on the imap side. The Telus tech never suggested trying this.

What am I risking here? My email could be intercepted somewhere along the way between servers and my computer?